Another Ebay low cost ex-mod purchase to add to the collection; not too much to say other the unit looks good inside, no sign of any previous battery leaks. Very nice item, I look forward to playing around with it on the bench.

Thank you for your efforts. It seems, the 505 DC current source is still pretty well in spec. (Maybe a little on the low side, but that could easily caused by the resistance of the test leads and the current shunts. The tolerances of the DMMīs are added anyways.)

So I have to say: I am really very impressed from this device.

When was the current source built? My guess would be: Pretty much 40 years ago.And works still fine...I donīt expect such a long lifetime from the items, nowadays produced.

BTW: Regarding the readings from your second Solartron 7150: 0.29 mA, 3.88 mA.Is there sadly a problem in the lower current range?

"When was the current source built? My guess would be: Pretty much 40 years ago."Quite possibly, they used the same case design I think for a good few years.

"BTW: Regarding the readings from your second Solartron 7150: 0.29 mA, 3.88 mA.Is there sadly a problem in the lower current range? "

VERY good point! looking at the service manual there is only 1 range for current and that is 2A; so a big jump like that looked quite odd; so i left both meters on for about 5 hrs; then re-did the readings for #1 and #2; but this time both meters were NULL'd and then i switched on the FILTER.